Sources, Dynamics and Management of Phosphorus in a Southern Baltic Estuary - The Baltic Sea Basin - page 383

release from the sediment into the lagoon, at least for a period of 1 month. This
is not possible for the Pomeranian Bay because we cannot say which processes
cause an increase in P concentrations, import from the lagoon or internal eutrophi-
cation. The result for the lagoon is shown for July 2000, where we observed a steep
increase in phosphorus concentrations in the water column. The difference between
the observed and simulated model concentrations is attributed to anoxic release from
the sediment.
This budget calculation has many weaknesses and limitations but it gives an idea
of the importance of different phosphorus sources. During summer, mineralization
processes contribute a similar amount of phosphorus like the Oder River (Fig. 18.5 ) .
With 280 t/month, the anoxic release is, in this very special situation, about four
times higher than the monthly river load. The lagoon does not serve as a sink for
phosphorus anymore but becomes a significant source for the Baltic Sea. About 100
t DIP is additionally released into the Baltic Sea during July 2000.
Fig. 18.5 Budget for dissolved inorganic phosphorus (DIP) in the Oder Lagoon for August 2000.
The content is the average during this month. The concentrations of organic phosphorus com-
pounds were largely constant during this month, while DIP concentrations showed a steep increase
in the lagoon. The total riverine P load into the lagoon was 246 t and the total P loss to the Baltic
Sea was about 340 t. The photographs give an impression of the poor water quality in and tourism
at the lagoon in summer